Hot work steel alloy



Patented Jan. 5, 1954 f res PATENT QFFICE.

HOT ZWOHK STEEL ALLOY ieonardivi. Kh ber Dunkirk. Y". assignor ta. Allegheny-'Ludlum Steel CorporatiomBrackenridge;-Pa-:; a: corporation of..Pennsy1vania.

Ng nlaw ilgi A lilicationOctobcr13g1951;

S J'iaLNo. 2511243:

r claims;-

h s'fi v tion tel'at stp. animmnved network alloy steel and p arlnite hQt...w.Q.r1;. alloy hav n a. hiehwab asien. resistance. and a o mpact stren t A h t-w n alloit av ne. wide;- usaeen di s. eta. usedi-in 111.01 1. r in hot: pressin shot extrusion Q f steelssalmmnum; copper; brass and any. metaknormaliy worked. at: elevated tempera: tures. Heretofore; aitihasibeen customaryato em ploy a 5% chromium: steel having -a low maximum carbon-content'of under 150%; usually well under-50%" (+30to .4z0%j-)- for such -an applicat-i'om It has been necessary'to maintain alower carbon content 120.. plioyide it with increased toughness and'to increase the high temperature fatigue failure of itstworking surface (phenomenon commonly, referredto. as heat checking). However, such an alloy has a relatively poor abrasion resistance and for this reason, has not been entirely satisfactory.

In endeavoring to solve the problem thus presented, I determined that it must be done in such a manner as to not adversely alter other required physical properties or adversely affect the heat treatment of the alloys. I discovered that the problem could be solved by increasing the carbon content above the maximum previously permissible amount and adding titanium as an alloying element, both within critical and essential ranges.

It thus has been an object of my invention to provide a practical solution to the problem.

Another object has been to develop a relatively inexpensive hot work alloy steel that will have a greatly increased abrasion resistance without a sacrifice of a good impact strength, toughness, heat checking and other required properties.

A further object has been to provide a titanium containing hot work steel alloy suitable for heat treatment and for use in hot dies.

In carrying out my invention, I discovered that the advantages of a lower carbon content could be retained by employing titanium in proper amounts as an alloying and carbide forming element and that a resulting, greatly increased abrasion resistance with a good impact strength could be obtained in the alloy without adversely 2 affecting its other properties. The alloys of my invention have the following contents:

Qj=0.(i0 to 1.25 Cr=3.00 to 6.00%. Ti= 2.00 to 3.507 Si=0.10 to 1.50%. Mo=0.50 to 2.007 W=.0.50to 2.00% Mn=un to 0;50% V=up tol.00%

Remainder iron with, incidental; impurities.

In. these: alloys; heat. treatment and, impact strength do not deviate from .theestandardsfiqz chromium, titaniumefree, .3 5 carbonhotwork steel alloy. A.measurelofi'therincreasedvhot abrae siOn resistance wasgobtainedby; subjecting: same ples.:0fwmya11 ys;.to theactibn of: a: rotating; disc of; a;super;hight,temperaturewalloy at. .1700?- undelzza pre sure. of; 4.0. Dundee The heateddisc wa ro ated hrou h dis ance. (121120.080 .ree'n periph ral:wheeltranel; at; azsneedi i; 1.00 Re. R. against the alloy samples. The weight loss of the test samples A of my alloy were recorded. Comparison alloy steels B and C were also subjected to the same test, see Table II.

The data of Table II clearly show the marked improved effect of titanium and additional carbon. That is, these two critical elements in properly proportionate ranges give the alloy a hardness and abrasion resistance under conditions of hot usage and as illustrated by Table III, without adversely affecting other requisite physicals. I have determined that as a minimum, the carbon content should be increased by .15 to 25% for each 1% additional titanium starting with .60% carbon and 2% titanium.

In Table III, specimens used were 1 inch round by 2 inches long and were oil quenched from the indicated temperatures. All were tempered for two hours at the indicated temperatures.

TABLE III Analysis Alloy A (mine), see Table II.

Alloy D (comparison):

C=.38%, Cr=5.04%, Si=1.00%, Mo=1.87%.

W=1.60%, Mn=.38%, and V=.20%.

ALLOY A Harden AS Shep Hardness Rkhg 321:2 tempering 2 ing qucnchei herd temp hardfracture RC mmg 900 F. 1,000F. 1,100 F. 1,200" F.

ALLOY D The titanium bearing alloy A is slightly lower in hardness because it is on the low side of the carbon content for the titanium content involved.

4 der iron with incidental impurities; the carbon 4 and titanium being highly essential in the ranges set forth, and the alloy being characterized by its high hot abrasion resistance with a good impact strength.

2. An alloy as defined in claim 1, wherein the maximum vanadium content is about .50%.

3. An alloy as defined in claim 1, wherein starting from the minimum specified amounts of carbon and titanium, the carbon is increased by at least .15 to 25% for each 1% increase in amount of titanium.

4. An alloy as defined in claim 1 wherein, its above defined abrasion resistance is retained after it has been tempered for about two hours at a temperature within a range of 900 F. to 1200" F.

5. An improved hot work die type of steel alloy which is tempered by heat treatment which contains about .85 to .95% carbon, about 5 to 5.5% chromium, about 3 to 3.25% titanium, about .90

to 1.10% silicon, about 1.10 to 1.30% molybdenum,

about 1.10 to 1.40% tungsten, about .30 to .50% manganese, about .50% maximum vanadium, and the remainder iron with incidental impurities; the alloy being characterized by its high hot abrasion resistance with good impact strength in its tempered condition.

6. An improved hot work die type of steel alloy having a high hot abrasion resistance combined with a good impact strength whose alloying ingredients consist essentially of about .60 to 1.25% carbon, about 3 to 6% chromium, about 2 to 3.5% titanium, about .10 to 1.5% silicon, about .50 to 2% each of molybdenum and tungsten, up to about .50% manganese, up to about 1 vanadium, and in which the carbon is increased by .15 to 25% for each 1% additional titanium within the stated ranges of each, starting with .60% carbon and 2% titanium.

LEONARD V. KLAYBOR.

References Cited in the file of this patent UNITED STATES PATENTS Number 

1. AN IMPROVED HOT WORK DIE TYPE OF STEEL ALLOY WHICH IS TEMPERED BY HEAT TREATMENT WHICH CONTAINS ABOUT .60 TO 1.25% CARBON, ABOUT 3 TO 6% CHROMIUM, ABOUT 2 TO 3.5% TITANIUM, ABOUT .10 TO 1.5% SILICON, ABOUT .50 TO 2% EACH OF MOLYBDENUM AND TUNGSTEN, UP TO ABOUT .50% MANGANESE, UP TO ABOUT 1% VANADIUM, AND THE REMAINDER IRON WITH INCIDENTAL IMPURITIES; THE CARBON AND TITANIUM BEING HIGHLY ESSENTIAL IN THE RANGES SET FORTH, AND THE ALLOY BEING CHARACTERIZED BY ITS HIGH HOT ABRASION RESISTANCE WITH A GOOD IMPACT STRENGTH. 